Vehicles with linear induction motors



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FIPSSGE 4 h515$368 ,m y l I i5 v 1 5 i 33974? M. POLOUJADOFF 3 VEHICLESWITH LINEAR INDUCTION MOTORS Filed Nov. 7, 1968 INS/5917732 HIM-IE z.zmou. ram/=1:

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3 513.333 VEHECLES WITH LIN EAR lNDUfiTiGN MGTQRS Michel Polujadotl,Grenoble, France, assignor to Merlin Gerin (Societe Anonyrne),firenoble, France Filed Nov. 7, 3958;. Ser. No. 774,960 flaims priority,application France, Nov. 17, 1967, 9

.4 1 int. (ll. HOZlt 41/02, 41/04 US. @l. Bill-13 l :laim

ABSTRAQ'E 6F THE BISCLGSURE Vehicle propelled by an electric linearmotor having an elongated stationary inductor producing a magnetictravelling field. A coil is located in the vehicle to be traversed bythe rlux of said field and to furnish the auxiliary service power in thevehicle.

other pick-up means, which transmit electric current to the movable unitor vehicle, and impose limitations which are particularly serious athigh speeds. It would be very regrettable to again introduce this sameproblem or pick= ing up current with regard to the auxiliary servicepower in the vehicles themselves.

The present invention is characterized by the fact that on the saidmovable vehicle there is arranged a winding which is traversed by themagnetic fiux or the said travelling field created by the said inductorin such a manner that an electromotive force is induced in the windingby the said inductor, which may be utilized as auxiliary service powerin the vehicle itself.

The requirements for auxiliary service power which consist essentiallyin power for the heating, lighting and possibly producing air cushionsfor lifting of th vehicle are relatively constant and small as comparedwith the propulsive power.

Therefore, there is no major drawback in taking, in accordance with thepresent invention, the energy necessary on the vehicle from the energywhich is transmitted by the inductor.

Naturally, the removal of this power has an elfect on the speed of thevehicle, but this eifect will be relatively slight and, in any event,can be allowed for in the design.

Other advantages and characteristics will become evident from thefollowing description of two embodiments of the invention shown in theaccompanying drawing given solely by way of illustration and not oflimitation. In the drawing:

FIG. 1 is a schematic perspective view of a vehicle with linear motor inaccordance with the invention;

FIG. 2 is an axial cross section through a variant embodiment of theinvention;

FIG. 3 is a section along the line ill-lil of PEG. 2.

Referring to FIG. 1, a stationary rail iii having the shape of aninverted T has a web 12 in which there are embedded polyphase inductioncoils 14, 16 which produce a sliding or travelling field in thedirection of the rail 10 when fed by a polyphase current, in the mannerwell known to those skilled in the art. A vehicle 18 straddles the web12 of the rail 10 and is capable of moving along a l e we 0 2313 3920Patented May is, rare said rail 16 under the action of propulsive forcesproduced by the travelling magnetic field cooperating with an armature,schematically represented by its magnetic circuits 20, 26? in FIG. 1,rigidly connected with the vehicle 18. Hovering and guiding of thevehicle 18 can be assured by cushions of air or any other means. Thearmature of the linear motor comprises windings (not shown), which mayor may not be shortcircuited, or is the seat of eddy currents in theconventional manner, and magnetic closure circuits 2!), 2,9 for thelines of force. At least one of these magnetic circuits 20 bears a coil22 traversed by the magnetic flux produced by the induction coils orconductors 14, 16. it can easily be seen that if the vehicle 18 is heldstopped and the inductor l4, i6 is fed with an alternating current, anelectromotive force will be induced in the coil 22 due to the variationof the flux passing through it. Electric power is thus available in thevehicle 13 by a simple magnetic pickup which avoids any brush or rubbingcontact. This electromotive force is a function of the speed ofdisplacement or" the vehicle 18 with respect to the speed of passage ofthe travelling field. it should be noted that it would be zero in thetheoretical limiting case of synchronism of the travelling field and thevehicle. Such temporary variations which occur may be compensated for byenergy storage means, for instance storage batteries (not shown), ofcourse combined with rectifiers, since the current induced is analternating current.

The removal of energy by the coil 22 from the travelling field obviouslyafi'ects the operation of the linear motor, but these removals of energyare relatively small as compared with the energies involved.Furthermore, the varia-= tions of these removals are not very great, andtheir infiuence on the speed of travel of the vehicle is practicallynegligible. Several coils 22 can be suitably arranged on the magneticcircuit so as a polyphase current is induced therein.

The energy induced in the coil 22 can serve to feed electricity to theauxiliaries of the vehicle, such as the heating devices, illuminatingdevices or air compressors, for instance for hovering and the like. Incase of the use of an induction winding having a substantialdistribution harmonic, one can contemplate efiecting the traction bymeans of an armature having thefundamental pole pitch of the inductioncoil and removing the power by means of a coil on the armature havingthe pole pitch of the largest harmonic of said inductor. in this case,by means of the power taken'from the secondary winding, a direct currentcan be passed through a rectifying system so as to synchronize the motorwith respect to the fundamental sliding field in a coil of the armature.

The invention is, or" course, by no means limited to the embodimentshown in FIG. 1. A variant embodiment is shown in FIGS. 2 and 3 in whichthe inductor 24 takes the form a tubular conduit whose inner face hasgrooves 26 therein receiving conductors of a coil, for instance a ringcoil, which produces a travelling field when fed by a polyphase currentin the customary manner. A cylindrical tubular armature 23 can movewithin the tubular indoctor 24, guided by any suitable means, forinstance means with air cushions, The tubular armature 28 mayconstitute, the frame of a vehicle moving along the path defined by thetubular rail 24. and propelled by the linear induction motor constitutedby the inductor 24 and the armature 2%. Such linear motors are wellknown to those skilled in the art and it is needless to describe them infurther detail. A pickup winding 32 is wound on the armature 28 and itcan easily be seen that it is traversed by the magnetic flux produced bythe inductor 24 in a manner comparable to the secondary of a transformerof which the winding coil '54 would be the primary. This electromotiveforce induced in the pickup Winding 32'is a function, as in the exampleillustrated by FIG. 1, of the slid- 3 ing of the iinear motor and inparticular of a frequency which varies depending on the speed of thevehicle.

The invention is by no means limited to the embodiments which have beenmore particularly described.

l. A vehicle driven by a linear induction motor, comprising: a tubularinductor extending along the vehicles path or" travel, means to generatea magnetic field which travels along the extent of said inductor, atubular armature rigidly mounted on said vehicle and disposed withinsaid tubular inductor, a toroidal pickup winding wound about saidarmature and rigidly connected thereto, whereby said magnetic fieldinteracts with said armature to drive said vehicle While any cutting oflines of flux by said pickup winding as the result of the vehicle andsaid magneric field not being perfectly synchronized, results in thegeneration of electrical power usetul for auxiliary pur poses in saidvehicle.

References Cited UNlTED STATES PATENTS 2,638,347 5/1953 Maggi 3lO-l2 X448,598 r 3/1891 Wheeler ct a1 310l3 DONOVAN F5 DUGGAN, Primary ExaminerU.S= Cl XR.

